A failure in the engine causing the detachment of one of the blades of the propeller can impact against the rear fuselage at high speed, sectioning it. In this emergency condition, the aircraft operates with only one engine generating a forward thrust, outside the plane of symmetry of the airplane. This thrust causes a yawing moment which must be balanced with a side aerodynamic force caused by the vertical stabilizer of the empennage, so that the aircraft can continue navigating stably. As the vertical stabilizer is located above the rear fuselage, this side aerodynamic force generates a torsion along the rear fuselage. If the blade impacts against the fuselage and sections it, the torsional strength of the fuselage is considerably reduced because the torsional rigidity of a closed section is proportional to the total area enclosed by the section, whereas the torsional rigidity of an open section is proportional to the material area of the section. It is therefore essential to design a section having multiple independent closed cells such that in the event of damage, there remains residually sufficient area with a closed section to support the torsion caused by the empennage in the emergency condition of an engine shutdown.
Propeller engines are usually located in the wing such that the detachment of a propeller can impact the central fuselage, in front of the wing. In this area of the fuselage, the torsion that the mentioned fuselage must support is relatively low, and is not a critical emergency condition. This has caused the residual torsional rigidity after impact to not be considered a critical factor in the design of fuselages up until now. However, this condition changes when the propeller engines are located at the rear part of the aircraft in front of the empennage, because then the torque generated by the empennage due to the failure of an engine is very high causing a catastrophic situation for the aircraft which must be prevented.
Another additional advantage is that the design of the fuselage according to the present invention considerably reduces the noise caused by the propellers of operating engines, which noise is propagated through the fuselage skin, reaching the passenger cabin.
The present invention is aimed at satisfying this demand.